WO1991005335A1 - Systeme de son optique numerique - Google Patents

Systeme de son optique numerique Download PDF

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Publication number
WO1991005335A1
WO1991005335A1 PCT/US1990/005211 US9005211W WO9105335A1 WO 1991005335 A1 WO1991005335 A1 WO 1991005335A1 US 9005211 W US9005211 W US 9005211W WO 9105335 A1 WO9105335 A1 WO 9105335A1
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Prior art keywords
bit
symbol
sensors
bits
codeword
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PCT/US1990/005211
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English (en)
Inventor
Elwyn R. Berlekamp
Lloyd R. Welch
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Eastman Kodak Company
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Application filed by Eastman Kodak Company filed Critical Eastman Kodak Company
Priority to EP90916000A priority Critical patent/EP0494267B1/fr
Priority to DE69016447T priority patent/DE69016447T2/de
Publication of WO1991005335A1 publication Critical patent/WO1991005335A1/fr

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
    • H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
    • H03M13/13—Linear codes
    • H03M13/15—Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes
    • H03M13/151—Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes using error location or error correction polynomials
    • H03M13/155—Shortening or extension of codes
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B31/00—Associated working of cameras or projectors with sound-recording or sound-reproducing means
    • G03B31/02—Associated working of cameras or projectors with sound-recording or sound-reproducing means in which sound track is on a moving-picture film
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/002—Recording, reproducing or erasing systems characterised by the shape or form of the carrier
    • G11B7/003—Recording, reproducing or erasing systems characterised by the shape or form of the carrier with webs, filaments or wires, e.g. belts, spooled tapes or films of quasi-infinite extent
    • G11B7/0032—Recording, reproducing or erasing systems characterised by the shape or form of the carrier with webs, filaments or wires, e.g. belts, spooled tapes or films of quasi-infinite extent for moving-picture soundtracks, i.e. cinema
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/03—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words
    • H03M13/05—Error detection or forward error correction by redundancy in data representation, i.e. code words containing more digits than the source words using block codes, i.e. a predetermined number of check bits joined to a predetermined number of information bits
    • H03M13/13—Linear codes
    • H03M13/15—Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes
    • H03M13/151—Cyclic codes, i.e. cyclic shifts of codewords produce other codewords, e.g. codes defined by a generator polynomial, Bose-Chaudhuri-Hocquenghem [BCH] codes using error location or error correction polynomials
    • H03M13/1515—Reed-Solomon codes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/29—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/29—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
    • H03M13/2903—Methods and arrangements specifically for encoding, e.g. parallel encoding of a plurality of constituent codes
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
    • H03M13/00—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes
    • H03M13/29—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
    • H03M13/2906—Coding, decoding or code conversion, for error detection or error correction; Coding theory basic assumptions; Coding bounds; Error probability evaluation methods; Channel models; Simulation or testing of codes combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes using block codes
    • H03M13/2927—Decoding strategies
    • H03M13/293—Decoding strategies with erasure setting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/79—Processing of colour television signals in connection with recording
    • H04N9/80—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
    • H04N9/802—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback involving processing of the sound signal
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N9/00—Details of colour television systems
    • H04N9/79—Processing of colour television signals in connection with recording
    • H04N9/87—Regeneration of colour television signals

Definitions

  • Karamon et al. propose matching the digital sound track to a conventionally recorded sound track on another portion of the film. If a portion the digital sound track is clearly different from the presumably more reliable conventional sound track, then that portion is discarded and the conventional sound track is used to fill the resulting void.
  • One disadvantage of this approach is that a problem with the digital sound track is not identified until it causes the digital sound track to be at least as bad if not worse in quality than the conventional sound track.
  • Another disadvantage is that, once a problem is identified, the only solution is to temporarily switch to the lower quality conventional sound • ;,''" '-structure.. track, causing a noticeable loss of quality. In many uses, this would be unacceptable. Accordingly,
  • the codeword inversion is performed by monitoring the number of such transitions for each possible inversion of the codeword, and then selecting that inversion having the greatest number of such transitions.
  • a row clock generator estimates the position of the transitions between horizontal rows of film bits by deciding whether the row clock leads or lags the actual timing of the horizontal film rows past the image sensor. It
  • each of the two compared values can be either positive or negative and can have a magnitude either greater or less than that of the other.
  • Each combination is an unambiguous indication of either a lead or a lag condition of the row clock signal with respect to the actual occurrence of row transitions at the image sensor.
  • the results of the comparison address a programmable-read-only-memory (PROM) which maps the eight possible combinations to appropriate lead or lag conditions. The algebraic sum of all the lead and lag conditions across the entire row is computed.
  • PROM programmable-read-only-memory
  • the modulus of a row clock counter is either decremented or incremented, depending upon whether the algebraic sum is positive or negative. Frequency of useful film bit transitions in the horizontal direction is maximized prior to recording by channel encoding the error correction symbols in each codeword so as to force the weight of the resulting symbol to be half the number of data bits per symbol. In other words, the occurrence of alternating zeroes and ones across a row of film bits is maximized.
  • errors in the horizontal film bit position estimates are corrected by computing partial sums of sines and cosines of successive film bit positions across a horizontal row. This computation takes advantage of the period location of pixels across the linear image sensor viewing each film bit row. Based upon the determination thus made of the center of each film bit, a particular one or a weighted pair of the image sensor pixels is chosen as representative of the current film bit.
  • each film bit thus located is measured and compared to predetermined magnitudes representative of binary zero and one values. If the measured magnitude is not sufficiently close to either, then an erasure flag is transmitted along with the closest binary data value.
  • the boundaries between received codeword symbols are determined in an electoral process in which the symbol weights of all possible boundaries are determined, with the boundary resulting in the symbol weight of the channel code being declared the winner. If this results in an indication that the current periodic set of symbol boundaries must be changed, the following steps are first taken before such a change is made. False indications of symbol boundary errors are eliminated by first attempting to achieve the requisite symbol weight by inverting those bits accompanied by an erasure flag. If such inversion succeeds, the symbols containing the inverted bits are flagged as erasures.
  • a non-decode flag is transmitted along with the present codeword.
  • the error correction code performance is optimized by first attempting to decode each codeword while using the erasure flags as error locator symbols. If the decoder finds no error value symbols for certain ones of the erased symbol locations, then the symbols in those locations are used as valid symbols in a second decoding attempt by the decoder. In the second attempt, the useful number of erasure and errors is limited to a predetermined number significantly less than the maximum capacity of the decoder. If the number of erasures and corrections exceeds the predetermined number when the decoder begins its second pass, then a mis-decode flag is transmitted.
  • the inversion of the erased bits results in fortuitously correct guess and therefore usually decreases the total number of erasures and errors below the predetermined number. This greatly enhances the reliability of the error correction decoder.
  • the probability of a mis-decode i.e., a decoded codeword which is apparently but not really correct is minimized to an insignificant level.
  • Fig. 1 is a pictorial diagram of digital optical film bits photographically recorded on a strip of film
  • Fig. 2 is a pictorial diagram illustrating image sensor pixels overlying the film bits of Fig.
  • Fig. 3 is a schematic block diagram of an encoding system embodying one aspect of the invention.
  • Fig. 4 is a flow diagram illustrating the operation of a Reed-Solomon encoder of the encoding system of Fig. 3;
  • Fig. 5 is a table illustrating' the contents of a six-to-eight encoder PROM of the encoding system of Fig. 3;
  • Fig. 6 is a diagram illustrating the format of encoded data generated by the encoder system of Fig. 3;
  • Fig. 7 is a diagram illustrating one example of film byte transition detected at one image sensor pixel scanning successive film bits as a function of time;
  • Fig. 8 illustrates useful data transitions in the encoded data generated by the encoder system of Fig. 3;
  • Fig. 9 is a graph illustrating the probability of occurrence of useful film bit transitions in the encoded data of Fig. 8;
  • Fig. 10 illustrates the juxtaposition of alternate rows for determining the number of useful film bit transitions in the encoded data;
  • Fig. 11 is a schematic block diagram illustrating the operation of a sub-codeword inverter in the encoder system of Fig. 3;
  • Fig. 12 is a schematic block diagram of a decoding system embodying another aspect of the invention.
  • Fig. 13 illustrates the relationship of the various types of useful film bit transitions to a lead and lag condition of a row clock signal of the image sensor with respect to the timing of successive film bit rows;
  • Fig. 14 is a schematic block diagram of a row clock generator in the decoding system of Fig. 12;
  • Fig. 15a is a pictorial diagram corresponding to Fig. 2;
  • Fig.'s 15b and 15c are graphs corresponding to Fig. 15a and illustrating the periodic nature of sines and cosines, respectively of the horizontal location in a row of film bits with respect to the film bit boundaries;
  • Fig. 15d is a graph corresponding to Fig. 15a and illustrating the film bit transition magnitude sensed by individual pixels of the image sensor as a function of horizontal location along the sensor;
  • Fig. 16 illustrates a simple test based upon cumulative sums of the sines and cosines of Fig.'s 15b and 15c to determine the error in the current estimate of the periodic horizontal locations of the centers of successive film bits;
  • Fig. 17 illustrates a more robust version of the test illustrated in Fig. 16;
  • Fig. 18 is a flow diagram illustrating the operation of a microprocessor in a phase word generator of the decoder system of Fig. 12;
  • Fig. 19 is a flow diagram illustrating the operation of a data desmearer of the decoder system of Fig. 12;
  • Fig. 20 is a block diagram of the data desmearer of the decoder system of Fig. 12;
  • Fig. 21 is a flow diagram illustrating the operation of a forward error corrector of the decoder system of Fig. 12;
  • Fig. 22 is a flow diagram illustrating an alternative embodiment of the operation of the forward error corrector of the decoder system of Fig. 12.
  • digital bits are photographically recorded in a "sound stripe" 100 along one edge of a strip of film 102 as individual black squares 104 organized into parallel horizontal rows 106 and parallel vertical columns 108.
  • a square —or "film bit”—104a which is clear represents a binary "one” while a film bit 104b which is opaque represents a binary "zero", for example.
  • the film bits 104 may have been photographically recorded onto the film 102 with virtually perfect accuracy, the film bits 104 must be accurately "read” by a linear image sensor as the film is longitudinally transported in a projector. Unfortunately, such a projector transports the film 102 in a manner characterized by significant fluctuations in film transport speed.
  • the linear image sensor 200 may be a charge coupled device (CCD) linear imaging array of individual pixels, for example, labelled pixel 1, pixel 2, pixel 3, etc., in Fig. 2.
  • CCD charge coupled device
  • the density of the opaque film bit 106c falls off slightly near the edges of the film bit, as illustrated by the curve labelled "p". Therefore, the best representation of a film bit and of corresponding film bit transitions is given by the CCD pixel nearest the center of the film bit.
  • the film bit center may wander under different CCD pixels.
  • One problem is how to always choose those
  • Encoding System Fig. 3 illustrates an encoding system which records digital optical signals in accordance with the invention.
  • An analog-to-digital converter 300 converts, for example, multi-channel analog audio sound signals to binary data streams comprising successive four-bit symbols, and multiplexes them into a single data stream of four-bit symbols.
  • An encoder 302 encodes the data stream in accordance with a BCH error correction code, such as a Reed-Solomon code, and inserts certain control and sychronization bits in predetermined locations.
  • a BCH error correction code such as a Reed-Solomon code
  • the encoder 302 grabs the next incoming block of 285 bits from'the converter 300 and inserts three control bits of zero value as the first, sixth and twelfth bit, respectively, in the data block.
  • the encoder 302 then prefixes and appends six-bit leading and trailing sync symbols, respectively, to the (now) 288-bit block.
  • the encoder 302 then divides the block into 49 six-bit symbols—including the leading sync symbol and not including the trailing sync symbol—and treats these 49 symbols as message symbols.
  • the encoder 302 computes 14 redundant six-bit check symbols in accordance with a code generator polynomial and appends these 14 check symbols to the block to form a 63-symbol codeword.
  • the code generator polynomial is a symmetrical or "palindromic" Reed-Solomon code generator polynomial. While in this example the code is an RS(63,49) code, it should be understood that other choices may be made for the number of bits in each audio byte generated by the converter 300, the number of bits in each block grabbed by the encoder 302 and the number of bits in each codeword symbol as well as the number of symbols in each codeword. Thus, palindromic codes other than RS(63,49) may be employed in the invention. Encoding to Maximize the Number of Useful Film Bit Transitions in the Horizontal Direction
  • the film bits when the film bits are to read or played back while the film is projected, distinguishing among the film bits in a given horizontal film bit row and maintaining symbol boundaries within the row is facilitated in the invention by encoding the data to be recorded as film bits in such a manner as to maximize the occurrence of alternating zeroes and ones (e.g., clear and opaque film bits) across each horizontal row.
  • this must be done without disturbing -li ⁇ the information content of the data stream.
  • the six-bit codeword symbols generated by the encoder 302 are applied in sequence to a 6-to-8 encoder programmable-read-only-memory (PROM) 304, which in turn produces a unique 8-bit symbol for each 6-bit codeword symbol received.
  • PROM programmable-read-only-memory
  • the contents of the PROM 304 are illustrated in Fig. 5.
  • the PROM 304 converts each 6-bit symbol to a unique 8-bit symbol whose weight is equal to 4—i.e., there are always four zero-value bits and four one-value bits in each eight-bit symbol. It so happens that there are only 64 . lx-bit symbols, which is less than the number of eight-bit symbols of weight four. As a result, the PROM 304 provides a unique eight-bit symbol for each six-bit codework symbol, thus avoiding any ambiguity.
  • Fig. 6 illustrates as a function of film bit position the encoded codeword block produced by the PROM 304.
  • the number of symbols (63) is divisible by 3, and therefore every third symbol in each block is labelled either A, B or C in Fig. 6.
  • the most significant bits of the second, third and fourth message bytes (labelled B00, C00 and A01, respectively) are the three control bits inserted by the encoder 302.
  • Fig. 6 illustrates the boundary of the messages symbols, the check symbols and the locations of the leading and trailing sync symbols (labelled S01 and S 0, respectively). It will be remembered that the leading sync symbol is one of the codeword symbols while the trailing sync symbol is not included in the codeword.
  • the luminance sensed by the CCD image sensor pixel 104a of Fig. 1 as the film 102 is transported in the projector is illustrated as a function of time in the graph of Fig. 7. If the image sensor 200 is at least nearly synchronized with the actual passage of the centers of successive film bit rows, then pixel positions 700 and 702 represent the occurrence of successive "snapshots" taken by the image sensor 200 at the pixel 104a. Note that the successive film bit luminance values in the film bit column underlying the pixel 104a "fall-off" near the film bit boundaries, because each film bit occupies less of the field of view of the CCD pixel as its center moves away from the pixel.
  • the image sensor is synchronized with the passage of successive film bit rows by tracking the difference between successive film bits.
  • the luminance values obtained at the successive sampling times corresponding to the pixel positions 700 and 702 of Fig. 7 are subtracted.
  • the parent and grandchild film bits represent opposite binary values, such a subtraction cannot distinguish film bit transitions.
  • the dashed line waveform of Fig. 7 is substituted instead of the solid line waveform, subtraction of successive luminance values would yield virtually no information.
  • Fig. 8 The problem is illustrated in Fig. 8, in which three successive rows of film bit data are shown in the relative location in which they are recorded on the film. Those columns having useful film bit transitions (in which the parent and grandch Id bits differ) are indicated by arrows. In this example, only some of the 40 columns shown have useful transitions. The goal is to increase the number of useful transitions so that they occur in greater than 50% of the columns.
  • This problem is solved in the invention by transforming each grandchild codeword so as to maximize the number of film bit transitions for which the parent film bit is different from the grandchild film bit within the same vertical film bit column. This results in a probability distribution of useful film bit transitions in which the median occurrence of useful film bit transitions is 54% and is never below 50%. However, such an inversion must be reversible upon playback so that the information content of the data is not lost.
  • a codeword is separable into sub-codewords of equal length, which in the case of RS(63,49) codewords is 31 symbols long, there being ree sub-codewords in this example.
  • Each sub-codeword comprises every third symbol of the codeword in this example.
  • every third symbol labelled A lies in one sub-codeword
  • every third symbol labelled B lies in a second sub-codeword
  • every third symbol labelled C lies in the third sub-codeword.
  • Each sub-codeword may be inverted and the resulting overall codeword is another codeword of the code.
  • a two-row delay circuit such as a memory 306.
  • the output of the PROM 304 is applied to the input of the two-row delay 306 and to a grandchild input of a sub-codeword inverter 308.
  • the output of the two-row delay 306 is applied to a parent input of the sub-codeword inverter 308.
  • the sub-codeword inverter 308 is illustrated in Fig. 11.
  • the grandchild film-bit data row is held in a grandchild register 750 while the parent film bit data row is held in a parent register 752.
  • the eight possible inversions of the grandchild codeword stored in the grandchild register 750 are generated by applying the contents of the grandchild register 750 to the address input 754 of a codeword inversion PROM 756.
  • sub-codeword A is inverted by simply adding the pattern 3F 000 000 (in hexidecimal) to the codeword
  • the sub-codeword B is inverted by adding the pattern 000 3F 000
  • the sub-codeword C is inverted by adding 000 000 3F.
  • the PROM 756 stores the results of the eight possible permutations of such additions for all 64 possible codewords. In the stored results, the three control bits are inverted as corresponding ones of the sub-codewords are inverted.
  • the PROM 756 By addressing the PROM 756 with the contents of the grandchild register 750, eight possible inversions of the codeword are loaded into the grandchild register 750 in succession and individually compared with the contents of the parent register 752 by a logic network of NAND gates 760 connected between corresponding bits of the two registers.
  • the outputs of all of the NAND gates 760 are polled by a poll logic circuit 762, which counts the number of mismatched bits between the parent and grandchild registers 752 and 750.
  • the poll logic circuit is connected to a memory 764 which stores this number as a score, so that a score is kept for each of the eight possible inversions of the grandchild codeword.
  • a logic circuit 766 detects which version has the highest score and declares that version as the winner to the address input 754 of the PROM
  • the corresponding inversion of the codeword is then loaded by the PROM 756 into the grandchild register 750.
  • This selected inversion is then transmitted by the sub-codeword inverter 308 to a demultiplexer 310 of Fig. 3 and thence to an optical recorder light emitting diode (LED) array 312 for recording of the serial stream of digital bits as film bits on the film 102.
  • LED optical recorder light emitting diode
  • a decoding system which reads the data from the film and decodes it is illustrated in Fig. 12.
  • the decoding system is included as part of a film projector 800 which transports the film 102 through a film gate illuminated by a high
  • the system further includes a CCD array system 804 (image sensor) comprising the linear CCD array 200 of image sensing pixels shown schematically in Fig. 2.
  • the CCD system 804 causes the CCD array to take a"snapshot"
  • the data desmearer 808 outputs binary data bits in accordance with the resemblance
  • the data desmearer 808 also outputs an erasure flag for each bit corresponding to a film bit which did not sufficiently resemble either a clear or opaque
  • An 8-to-6 converter converts the eight-bit encoded symbols to six-bit RS(63,49) symbols. Prior to this conversion, symbol boundaries are checked or corrected by the desmearer 808 by sensing which of eight possible periodic
  • a codeword sync acquisition circuit 814 detects the presence of the leading and trailing sync symbols to synchronize a forward error corrector 816 so that it grabs each incoming codeword as it is received from the 8-to-6 converter 812.
  • the forward error corrector 816 employs the erasure flags as error location symbols in decoding and correcting the received codeword.
  • the forward error corrector 816 takes advantage of the corrections performed by the desmearer 808 and the 8-to-6 converter 812 by first verifying their efficacy and then deregarding corresponding erasure flags.
  • Fig. 13 For film bit transitions that meet the criteria Fig. 7 (i.e., the parent and grandchild film bits in a given column differ) a conclusion may be drawn as to whether the CCD array 200 is being triggered by the row clock signal slightly ahead of the center of the current row ("lead") or slightly behind it ("lag").
  • the vertical axis is the algebraic difference between the luminance of a given pixel in the current row and the average luminance across all pixels in the current row.
  • the horizontal axis is the algebraic difference between the luminance of the same pixel in the previous row and the average luminance across all pixels in the previous row.
  • a vector such as the vector V illustrated in Fig. 13 specifies a pair film bit values of current and previous film bit rows within a given film bit column.
  • Each quadrant of the graph of Fig. 13 is divided along a 45 degree bisector, all vectors lying in one half of the quadrant indicating a "lead" condition and all vectors lying in the other half indicating a "lag” condition. If a vector lies along one of the 45 degree bisectors, no information regarding the timeliness of the row clock signal can be gleaned.
  • the row clock signal which triggers each
  • “snapshot" taken by the CCD imaging array 200 is regulated in accordance with the foregoing principles by the row clock generator 806 of the decoding system of Fig. 12.
  • the row clock generator 806 is illustrated in the functional block diagram of Fig. 14.
  • an adder/accumulator function 820 receives from the CCD array system 804 the luminance values of all the film bits in the current film bit row and computes the average luminance across the entire row.
  • a subtractor function 822 subtracts the average luminance from the luminance values of each film bit in the row and transmits the resulting "normalized" luminance values to a one-row delay function 824 and to one address sub-port of a lead/lag PROM 826, one film bit at a time.
  • the lead/lag PROM 826 receives at another address sub-port the corresponding normalized luminance values of the previous film bit row from the one-row delay function 824, one film bit at a time. Together, the two address sub-ports comprise the address port of the lead/lag PROM 826.
  • the lead/lag PROM 826 implements the diagram of Fig. 13. For this purpose, it stores for , 11 possible combinations of luminance value pairs of the current and previous film bit rows the appropriate lead or lag indications in accordance with the diagram of Fig. 13. For each film bit pair across one row, the lead/lag PROM transmits either a lead or lag or "hold" (do nothing) indication to an up/down counter 828. The contents of the up/down counter 828 is reset at the beginning of each film bit row. The up/down counter 828 counts up one or down one in response to each lead or lag command, respectively, received from the lead/lag PROM 826.
  • the up/down counter 828 contains the algebraic sum of all lead and lag conditions of the current row, which is a reliable indication of whether the row clock signal actually leads or lags the coincidence in time of the center of the current film bit row with the linear CCD imager array 200 of the CCD array system 804.
  • the contents of the up/down counter 828 is applied to the input of a row clock adjustment PROM 830.
  • the row clock adjustment PROM 830 responds by producing a binary number equal to the number of clock cycles N normally required by the CCD imager system 804 to cycle and refresh all of its pixels in the well-known fashion (typically 280) plus a positive or negative number x (typically +5 or -5). Whether x is positive or negative depends upon whether the contents of the up/down counter 828 indicates a preponderance of lead or lag conditions, respectively, for the current film bit row. This binary number is then employed as the modulus of a counter 832 whose output is the row clock signal controlling the CCD array system 804.
  • the row clock adjustment PROM correlates all possible values which the contents of the up/down counter may assume to either N+x or N-x as appropriate, in accordance with the foregoing description.
  • the PROM's 826 and 830 are readily programmed by the skilled worker in accordance with the foregoing description.
  • Phase Word Generator While the row clock generator 806 assures that the CCD array 200 is triggered in the middle of the current film bit row, thus centering each image sensor pixel with respect to the film bit rows in the vertical direction, it is also necessary to select those image sensor pixels most nearly centered in the horizontal direction with respect to the film bits. Such a selection is controlled by the phase word generator 810 of the decoding system of Fig. 12.
  • the phase word generator 810 employs an angular coordinate system for specifying the horizontal location along the linear imager array 200 (illustrated in Fig. 2) with respect to the film bit locations.
  • This angular coordinate system is illustrated in Fig. 2.
  • the horizontal position is denoted ⁇ and is expressed in units in which the width W of one film bit is defined as unity.
  • the width w of each CCD imaging pixel in the linear array 200 (which is presumed to be the same for all such pixels) is denoted ⁇ , and is expressed in the same units wherein the width W of one film bit is defined as unity.
  • .525 i.e., about half a film bit width.
  • the locations of the centers of each of the pixels in the linear array 200 expressed in terms of the angle ⁇ are known.
  • the goal, then, is to always know the value of ⁇ at the center of each film bit so that the desmearer 808 may select for each film bit the CCD pixel most nearly centered over the film bit, despite lateral wandering of the film with respect to the linear array 200.
  • the angular error A may be estimated by computing:
  • phase word generator 810 performs the computations in a microprocessor 810a of equations (1.) through (4.) above to determine S and C .
  • the microprocessor 810a then performs the tests (a) through (d) above to estimate the angular error A in accordance with the chart of Fig. 16.
  • the microprocessor 810a then changes the values of ⁇ and ⁇ stored in a phase word register 810b to compensate for the error.
  • Fig. 17 shows how to estimate A to within an error of one-sixteenth of a film bit width W by simply determining (a) which one of S and C is the greater, (b) whether their sum is a negative number, (c) whether their difference is negative number and (d) whether each of them is a positive or negative number.
  • the phase word generator 810 performs the computations in a microprocessor 810a of equations (1.) through (4.) above to determine S and C .
  • the microprocessor 810a then performs the tests (a) through
  • the microprocessor 810a (or its equivalent in dedicated logic circuits) performs the algorithm depicted in the flow chart of Fig. 18.
  • the microprocessor maintains the definitions of equations (1.) through (5.) above in blocks 840, 842 and 844. It further defines the partial sums of block 846 and block 848.
  • the microprocessor 810a then performs the computations of block 850 using the partial sums defined previously in the preceeding blocks to produce an average correction D .
  • the microprocessor 810a then employs the average correction D to update the values ⁇ ' reg ' and ⁇
  • the first task of the data desmearer 808 of the decoding system of Fig. 12 is to use the angular values ⁇ and ir ⁇ currently stored in the phase register 810b to choose only those pixels in the linear array 200 which are most nearly centered in the horizontal direction over respective film bits in the current horizontal film bit row.
  • the data desmearer 808 does this by performing the process illustrated in the block diagram of Fig. 19. (For this purpose, the data desmearer 808 may be either a programmed microprocessor or dedicated logic hardware, either of which is readily adapted by the skilled worker to perform the process of Fig. 19.)
  • ⁇ n is ⁇ tr-ed in the -24- phase word register 810b and is the distance between a reference point such as sound stripe edge and the center of the first pixel in the linear array, as illustrated in Fig. 2.
  • This initializing step is 5 depicted in block 860 of Fig. 19.
  • the new value of ⁇ is then computed by adding 2 ⁇ r ⁇ (taken from the phase word register 810b) to the old value (block 862). A determination is then made as to whether this change in ⁇
  • the desmearer 808 knows how to do this because it knows the location value ⁇ of the center of each pixel in the array 200, as illustrated in Fig. 2.
  • this value depends upon the number of film bits per horizontal row and the number of CCD imager pixels spanning the row, which in the present example is approximately 161 and
  • the desmearer 808 grabs the luminance value of either the next or the previous even numbered pixel in the array 200.
  • the object here is to select two adjacent pixels
  • a weighted luminance value dn' is then computed from the luminance values dn od,d, and dn even of the odd and even pixels which have now been grabbed.
  • the weighting is based upon the 35 relative proximity of each of the two pixels to the center of the film bit, such that if one of the two pixels is directly centered over the film bit, the other pixel is completely ignored, while if the two pixels symmetrically span the film bit, they are weighte equally.
  • 874a defining the weight of the odd pixel luminance value
  • 874b defining the weight of the even pixel luminance value
  • 874c depicting the computation of the weighted luminance value from the odd and even luminance values.
  • the predetermined threshold may be set such that an erasure flag bit is transmitted whenever dn* is not within 33% of either d Q or d..
  • the luminance values d_ and d. are readily predetermined by the skilled worker by simply noting the luminance values of CCD pixels centered over clear and opaque film bits, respectively.
  • the process of Fig. 19 then returns to block 862 to update ⁇ using the latest value of ⁇ stored in the phase word register 810b, and the foregoing cycle is repeated until th ⁇ end of the current horizontal film bit row is reached.
  • First Level Error Correction, Symbol Sync Detection and 8-to-6 Conversion Channel Decoding by the Data Desmearer 808 is illustrated in the schematic block diagram of Fig. 20.
  • the circuit of Fig. 20 takes advantage of the 6-to-8 channel encoding performed by the 6-to-8 encoder PROM 304 of the encoder system of Fig. 3 and of the erasure flag bits produced in accordance with the process of Fig. 19 to correct and maintain symbol-to-symbol boundaries and to perform a first level error correction process.
  • the data bits produced in the step of block 878 of the process of Fig. 19 are stored sequentially in an eight-bit data register 890 while the corresponding erasure flag bits produced in the step of block 880 of the process of Fig. 19 are stored in corresponding locations in an erasure flag register 892.
  • the contents of the data register 890 are applied to the address input of a weight-4 PROM 894.
  • the PROM is programmed so as to transmit a one-bit only if the eight bit sequence in the data register has a weight of four. It will be recalled that the 6-to-8 encoder PROM 304 of the encoder system of Fig.
  • the output of the weight-4 PROM 894 sets a flip-flop 896 controlling one address bit of a scoring PROM 898.
  • the scoring PROM 898 is part of a symbol boundary control loop 900, including a score random access memory (RAM) 902, an input latch 904, an output latch 906, an output flip flop 908, a comparator 910 and a modulus eight (mod 8) counter 912.
  • RAM score random access memory
  • the number of bits at each input and output of each of the foregoing elements of the symbol boundary control loop 900 is indicated in Fig. 20.
  • the scoring PROM 898 As soon as the scoring PROM 898 receives a score of 63, it declares the current cycle of the mod-8 counter to be the "winner"—i.e., the current cycle defines the proper boundary between successive eight-bit synbols in the data bit stream received by the data register 890. This cycle number (a three bit number) is stored in the latch 906. Then, as each winner is declared by the scoring PROM 898, the comparator compares the current cycle of the mod-8 counter 912 with the cycle of the previous winner (the contents of the latch 906). If there is a match, this means that the symbol boundary has not changed since the previous symbol and therefore there has been no detected symbol boundary error.
  • the comparator 910 enables a serial-to-parallel flip-flop 914 at the output of the data register 890 so that the current contents of the data register is output as an eight-bit symbol. If there is a mismatch, however, the comparator 910 causes a mute flag to be transmitted by a logic gate 916. This mute flag identifies the current symbol to the forward error corrector 816 of Fig. 12 as being one in which the symbol boundary is incorrect and therefore as a useless symbol. As will be explained hereinbelow, this mute flag warns the forward error corrector that the entire codeword may not be correctable, due to the loss of symbol synch, and should therefore be muted. In this case, the user may perform other procedures. For example, if the data represents digital audio data, the user may fill in for the muted codeword by performing audio interpolation.
  • the scoring PROM 898 After declaring a "winner", the scoring PROM 898 prevents overly frequent changes to the symbol boundary by preventing the score of any other one of the eight memory locations from increasing, although any score is allowed to decrease, including the score of the "winner". If the winner's score decreases below the maximum (63), then there is no declared "winner” and any score is allowed to advance in the manner described above. This latter feature is implemented by the connection between the output of the comparator 910 and the flip-flop 908. The output of the flip-flop 908 is connected to an address input of the scoring PROM 898 so as to disable the PROM 898 from advancing the scores stored in the score RAM 902 as long as the current declared winner is the same as the previous declared winner.
  • First Level Bit Error Correction :
  • the eight bits stored in the serial data register 890 are simultaneously applied through an arithmetic logic unit (ALU) 918 to eight parallel address bit inputs of a correcting weight «4 PROM 920.
  • the correcting weight «4 PROM 920 determines whether the weight of the eight bits is four. If so, this indicates that the eight bits are most likely correct and can therefore be transmitted "as is" to the forward error corrector 816. However, if the weight is not equal to four, then the PROM 920 transmits inverting flag through a latch 922 to the ALU 918.
  • the ALU 918 attempts to correct individual bits stored in the data register 890 by logically ORing them with corresponding bits stored in the erasure flag register 982. On the other hand, if the weight is greater than four, the ALU 918 AND's each of the bits stored in the data register 890 with corresponding bits in the erasure register 892, these latter results being applied to the PROM 920. The results of this correction attempt are then transmitted to the eight address inputs of the PROM 920, which again determines whether they are of weight four. If the weight is now found to be four, then the attempt has succeeded and the eight bit symbol is converted by the PROM 920 to the corresponding six-bit symbol for transmission to the forward error corrector 816. Otherwise, if the symbol weight is still not four, the correction attempt has failed. At this point, no further correction attempts are made by the ALU 918.
  • the PROM 920 issues an erase flag to the forward error corrector 816.
  • the forward error corrector 816 responds to this erase flag by treating the current symbol as an erasure.
  • the skilled worker may readily implement the foregoing functions in the data desmearer 808 by appropriate logic circuitry 924 and an appropriately programmed output PROM 926 connected to the PROM 920 as illustrated in Fig. 20.
  • the data desmearer 808 provides the forward error corrector 816 with either a six-bit symbol, or a symbol erasure flag or a mute flag.
  • the forward error corrector 816 performs the error correction required to recover the information (e.g., digital audio) bits from each RS(63,49) codeword, using well-known techniques.
  • the codeword is delineated by the leading and trailing sync symbols discussed previously herein in connection with Fig. 6 and comprises 63 six-bit symbols received in succession from the data desmearer 812.
  • the delineation of the codeword is performed by the codeword sync acquisition circuit 814 using techniques well-known in the art.
  • the forward error corrector employs a Reed-Solomon decoder algorithm which can correct the codeword as long as the sum of the number of erasures (errors of known locations) and twice the number of error (of unknown locations) does not exceed r, the number of check symbols in the codeword, which in this case is 14.
  • r the number of check symbols in the codeword
  • h may be on the order of 10 or 12 in the present example of RS(63,49).
  • the forward error corrector does this in a manner which optimizes the decoding correction performance, in accordance with the error correction process illustrated in Fig. 21.
  • the forward error corrector 816 instead first assumes that some of the erasure flags were erroneously issued and therefore tries to decode the codeword as if there were no erasures (block 934). If it finds the codeword is decodable (block 936), it outputs the decoded/corrected codeword (block 938) . Otherwise, it issues a mute flag to the user, signifying that the codeword is undecodable (block 940).
  • the forward error corrector 816 decodes the codeword using all of the erasure flags as erasure locations (block 942). If the codeword is not decodable, the forward error corrector 816 issues a codeword mute flag to the user (block 945). If the codeword is decodable (block 944), the forward error corrector 816 determines how many of the 63 codeword symbols accompanied by an erasure flag were error-free. This number is then subtracted from S (the number of apparent erasures, discussed above) to obtain the number of true erasures S' (block 946). Also, the number of erroneous symbols found which were not accompanied by an erasure flag is determined.

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Abstract

On corrige les estimations concernant les positions horizontales et verticales des bits numériques sur un film en suivant les limites de transition des bits dans les direction horizontales et verticales. La fréquence des transitions utiles des bits du film est maximisée avant l'enregistrement au moyen de la correction des erreurs codant les bytes audio numériques et en inversant ensuite de manière sélective les portions symétriques de chaque mot code. La fréquence des transitions des bits du film utiles dans la direction horizontale est maximisée avant l'energistrement au moyen du codage en canaux des symboles de correction d'erreur dans chaque mot code afin d'obliger le poids du symbole résultant à être la moitié du nombre de bits de données par symboles. Au cours de la lecture, on corrige les erreurs situées au noveau des estimation de position du bit horizontal sur le film. On mesure et on compare la grandeur de chaque bit du film situé, à des grandeurs prédéterminées représentant les valeurs binaires zéro et un. Les limites entre les symboles de mot codes reçus déterminées au moyen d'un procédé de vote au cours duquel sont déterminés les poids symboles de nombreuses limites. Les fausses indications d'erreurs de limite de symbole sont éliminées par une correction d'erreur de bit de premier niveau. Une dernière étape de correction des erreurs est ensuite réalisée en utilisant un algorithme de décodage de Reed-Solomon.
PCT/US1990/005211 1989-09-29 1990-09-17 Systeme de son optique numerique WO1991005335A1 (fr)

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WO1992014239A1 (fr) * 1991-02-04 1992-08-20 Dolby Laboratories Licensing Corporation Support de stockage et appareil et procede pour extraire des informations de ce support par surechantillonnage
EP0544090A1 (fr) * 1991-10-14 1993-06-02 Sony Corporation Procédé pour l'enregistrement d'un signal audio numérique sur un film cinématographique
EP0574136A2 (fr) * 1992-06-10 1993-12-15 SONY ELECTRONICS INC. (a Delaware corporation) Support photosensible et enregistrement photographique de données audio-digitales sur celui-ci
US5550603A (en) * 1992-11-30 1996-08-27 Sony Corporation Motion picture film with digital sound track
US5621489A (en) * 1992-06-10 1997-04-15 Sony Corporation Medium having photographically recorded digital audio bits
US5639585A (en) * 1995-08-31 1997-06-17 Sony Corporation System for photographically recording digital data and analog soundtrack, and medium having digital data and analog soundtrack recorded thereon
US5761349A (en) * 1994-02-23 1998-06-02 Sony Corporation Apparatus for reading optical data from a motion picture film and a light source therefor
CN105072058A (zh) * 2015-08-25 2015-11-18 许继集团有限公司 一种基于光纤传输的数据正反相位编码方法及数据传输方法

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AU2002214955A1 (en) * 2000-09-11 2002-03-22 Bts Holding International B.V. Device and method for reproducing photographic sound recordings
US6972829B2 (en) * 2003-11-17 2005-12-06 Nt Audio Visual Supply, Inc. Film soundtrack reviewing system

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EP0231380A1 (fr) * 1985-04-23 1987-08-12 Dai Nippon Insatsu Kabushiki Kaisha Procede d'enregistrement de donnees sur cartes d'enregistrement de donnees optiques

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US4600280A (en) * 1984-07-16 1986-07-15 Clark Lloyd D Digital audio recording/playback system for motion picture film
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EP0231380A1 (fr) * 1985-04-23 1987-08-12 Dai Nippon Insatsu Kabushiki Kaisha Procede d'enregistrement de donnees sur cartes d'enregistrement de donnees optiques
EP0227380A1 (fr) * 1985-12-11 1987-07-01 Canon Kabushiki Kaisha Moyen d'enregistrement d'informations et procédé pour reproduire des informations à partir de ce moyen

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US5544140A (en) * 1991-02-04 1996-08-06 Dolby Laboratories Licensing Corporation Storage medium and apparatus and method for recovering information from such medium by oversampling
US5710752A (en) * 1991-02-04 1998-01-20 Dolby Laboratories Licensing Corporation Apparatus using one optical sensor to recover audio information from analog and digital soundtrack carried on motion picture film
WO1992014239A1 (fr) * 1991-02-04 1992-08-20 Dolby Laboratories Licensing Corporation Support de stockage et appareil et procede pour extraire des informations de ce support par surechantillonnage
AU657744B2 (en) * 1991-02-04 1995-03-23 Dolby Laboratories Licensing Corporation Storage medium and apparatus and method for recovering information from such medium by oversampling
US5347509A (en) * 1991-02-04 1994-09-13 Dolby Laboratories Licensing Corporation Recovering digital information represented by multi-dimensionally encoded symbols carried by an information storage medium
EP0544090A1 (fr) * 1991-10-14 1993-06-02 Sony Corporation Procédé pour l'enregistrement d'un signal audio numérique sur un film cinématographique
US5666185A (en) * 1991-10-14 1997-09-09 Sony Corporation Method for recording a digital audio signal on a motion picture film
US5471263A (en) * 1991-10-14 1995-11-28 Sony Corporation Method for recording a digital audio signal on a motion picture film and a motion picture film having digital soundtracks
EP0574136A3 (fr) * 1992-06-10 1994-01-12 SONY ELECTRONICS INC. (a Delaware corporation) Support photosensible et enregistrement photographique de données audio-digitales sur celui-ci
EP0574136A2 (fr) * 1992-06-10 1993-12-15 SONY ELECTRONICS INC. (a Delaware corporation) Support photosensible et enregistrement photographique de données audio-digitales sur celui-ci
US5621489A (en) * 1992-06-10 1997-04-15 Sony Corporation Medium having photographically recorded digital audio bits
US5453802A (en) * 1992-06-10 1995-09-26 Sony Electronics Inc. Method and apparatus for photographically recording digital audio and a medium having photographically recorded digital sountracks
US5841513A (en) * 1992-11-30 1998-11-24 Sony Corporation Apparatus for reproducing sound signals recorded on a motion picture film with digital sound track
US5550603A (en) * 1992-11-30 1996-08-27 Sony Corporation Motion picture film with digital sound track
US5761349A (en) * 1994-02-23 1998-06-02 Sony Corporation Apparatus for reading optical data from a motion picture film and a light source therefor
US5639585A (en) * 1995-08-31 1997-06-17 Sony Corporation System for photographically recording digital data and analog soundtrack, and medium having digital data and analog soundtrack recorded thereon
CN105072058B (zh) * 2015-08-25 2018-05-25 许继集团有限公司 一种基于光纤传输的数据正反相位编码方法及数据传输方法
CN105072058A (zh) * 2015-08-25 2015-11-18 许继集团有限公司 一种基于光纤传输的数据正反相位编码方法及数据传输方法

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JPH05501025A (ja) 1993-02-25
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EP0494267B1 (fr) 1995-01-25
DE69016447D1 (de) 1995-03-09

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